scholarly journals Thermal preference influences depth use but not biomass of predatory fishes in response to lake morphometry

2019 ◽  
Author(s):  
Timothy J. Bartley ◽  
Matthew M. Guzzo ◽  
Kevin Cazelles ◽  
Alex Verville ◽  
Bailey C. McMeans ◽  
...  

ABSTRACTTop predators’ responses to environmental conditions shape food web architecture and influence ecosystem structure and stability. Yet the impacts of fundamental properties like ecosystem size and morphometry on top predators’ behaviour are poorly understood. We examined how lake morphometry impacts the behaviour (inferred by depth use) of three key fish top predators—the cold-adapted lake trout, the cool-adapted walleye, and the warm-adapted smallmouth bass— which can each strongly impact local food web structure. We used catch-per-unit-effort data from nearly 500 boreal lakes of Ontario, Canada to evaluate the role of thermal preference in dictating mean depth of capture and biomass index in response to lake morphometry. We found evidence that thermal preferences influence how species’ depth use and biomass changed with lake size, proportion of littoral area, and maximum lake depth, although we found no relationship with lake shape. However, found no strong evidence that lake morphology influences these species’ biomasses, despite theory that predicts such a relationship. Our results suggest that some aspects of lake morphometry can alter habitat accessibility and productivity in ways that influence the behaviour and biomass of these top predator species depending on their thermal preferences. Our results have implications for how lake food webs expand and contract with lake morphometry and other key abiotic factors. We argue that several key abiotic factors likely drive top predator depth use in ways that may shape local food web structure and play an important role in determining the ultimate fate of ecosystems with environmental change.

2013 ◽  
Vol 70 (12) ◽  
pp. 1805-1812 ◽  
Author(s):  
Allison Schein ◽  
Simon C. Courtenay ◽  
Karen A. Kidd ◽  
K. Alexander Campbell ◽  
Michael R. van den Heuvel

This study compared food web structure in eutrophied Ulva lactuca-dominated areas within an estuary in the Southern Gulf of St. Lawrence, with Zostera marina beds within the same estuary. The estuarine food web consisted only of primary producers, mesograzers, and secondary grazers, with the absence of piscivorous top predators. It was hypothesized that the altered plant habitat would lead to structural changes in the food web and the dominance of benthic carbon. Stomach contents from mummichog (Fundulus heteroclitus), fourspine stickleback (Apeltes quadracus), and American eel (Anguilla rostrata) showed that only mummichog had significant differences in prey items between the different habitats. Stable isotopes showed that there were no significant differences in the food web structure and individual species’ 13C values. A 13C spike in particulate organic matter during the onset of anoxia in July, presumably due to bacterial blooms, indicated the complete dominance of benthic carbon the pelagic food web during this month. Thus, blooms of heterotrophs during anoxic events may have the greatest influence on nutrient cycling in estuaries undergoing eutrophication.


2018 ◽  
Vol 8 (1) ◽  
Author(s):  
Massimiliano Drago ◽  
Valentina Franco-Trecu ◽  
Angel M. Segura ◽  
Meica Valdivia ◽  
Enrique M. González ◽  
...  

2019 ◽  
Vol 76 (11) ◽  
pp. 1929-1939 ◽  
Author(s):  
Kate Prestie ◽  
Iain D. Phillips ◽  
Douglas P. Chivers ◽  
Timothy D. Jardine

Lake food web structure dictates the flow of energy and contaminants to top predators, and addition of invasive species can shift these flows. We examined trophic position (TP), proportional reliance on the littoral zone (Proplittoral), and mercury (Hg) concentrations across the life-span of two predatory fishes, walleye (Sander vitreus) and northern pike (Esox lucius), in lakes with and without invasive virile crayfish (Faxonius virilis). The littoral zone was the dominant foraging zone for both species regardless of size, accounting for 59% and 80% of the diet of walleye and pike, respectively. Both species increased in TP and Hg with body size, as did crayfish. Walleye in crayfish-present lakes had lower Proplittoral, TP, and Hg concentrations compared with non-present lakes, but trophic magnification of Hg through the food web was consistent across all six lakes. These findings underscore a strong role for the littoral zone in channeling energy and contaminants to higher trophic levels and how invasive species can occupy new habitats at low abundance while altering food web structure and contaminant bioaccumulation.


2020 ◽  
Author(s):  
Aaron M. Ellison ◽  
Nicholas J. Gotelli ◽  
Leszek A. Błędzki ◽  
Jessica L. Butler

ABSTRACTPhytotelmata, the water-filled habitats in pitcher plants, bromeliad tanks, and tree-holes, host multitrophic food webs that are model experimental systems for studying food-web structure and dynamics. However, the plant usually is considered simply as an inert container, not as an interacting part of the food web. We used a response-surface and factorial field experiment to determine effects of nutrient enrichment (multiple levels of NH4NO3, PO4, and captured prey), top predator (removed or present), and the plant itself (with or without plastic tubes inserted into the pitchers to isolate the food web from the plant) on the macrobial food web within the modified leaves (“pitchers”) of the carnivorous pitcher plant Sarracenia purpurea. Connection to the plant, addition of NH4NO3 and removal of the top predator significantly increased the food web’s saturation, defined as its trophic depth and number of interactions. No effects on food-web saturation resulted from addition of PO4 or supplemental prey. Plants such as S. purpurea that create phytotelmata are more than inert containers and their inhabitants are more than commensal inquilines. Rather, both the plant and the inquilines are partners in a complex network of interactions.


2016 ◽  
Vol 23 (2) ◽  
pp. 673-685 ◽  
Author(s):  
Nicholas A. C. Marino ◽  
Diane S. Srivastava ◽  
A. Andrew M. MacDonald ◽  
Juliana S. Leal ◽  
Alice B. A. Campos ◽  
...  

2017 ◽  
Vol 27 (4) ◽  
pp. 1190-1198 ◽  
Author(s):  
Joshua J. Thoresen ◽  
David Towns ◽  
Sebastian Leuzinger ◽  
Mel Durrett ◽  
Christa P. H. Mulder ◽  
...  

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